Outline that follows character?
You can get an outline in the viewport with a simple hack that involves a solidify modifier and a second black material.


The image contains all the setup you need. To summarize, what we are doing is:


Add a second material to the mesh you want to have the outline one, set color to black.
Add a solidify modifier with the above settings, which creates an inverted normal shell around the original mesh. Assign it the outline material using Material Index Offset.
Turn on 'Backface Culling' in the viewport so that the backface of the black outline is not visible.
To make this setup work in Blender Render and Cycles, check this answer.